(1) Field of the Invention
The present invention relates generally to underwater transducers, and more particularly to a transducer shell assembly, and a transducer using the shell assembly for bimodal operation at two distinct frequencies.
(2) Description of the Prior Art
A variety of mobile underwater transducer devices are used by the Navy. Some are used to simulate sonar characteristics of submarines for anti-submarine warfare (ASW) training, while others are deployed as sonar and torpedo countermeasures. In performing their various functions, these devices use underwater transducers to transmit and/or receive acoustic signals. Different types of transducers are used depending on the required frequency of operation. For example, split-ring transducers are used for low frequency operation below approximately 1 KHz. For higher frequency operation of approximately 2.5 KHz or higher, solid-ring (ceramic) transducers are used in order to support a breathing mode (i.e., radial expansion and contraction) of operation. Devices that give the user the option of high or low frequency operation are generally preferred. However, because of the vastly different construction of these two types of transducers, two separate transducer assemblies are used to support the different operation frequencies. This increases the overall weight and cost of underwater devices that utilize transducers.